1. Field of the Invention
This invention generally relates to a seal arrangement for propeller drives for ships. More particularly, the seal arrangement of the present invention relates to a seal arrangement for being disposed between two concentric propeller shafts rotating in opposite directions. Such seal arrangements for propeller drives for ships with two concentric propeller shafts rotating in opposite directions from one another, generally have a seal for the outer shaft, sealing the outer shaft to the ships hull, and a seal for the inner shaft, sealing the inner shaft to the outer shaft. Such seals can be designed as lip seals, wherein the seals are connected to the stern tube of the outer shaft in a water-tight manner.
2. Background Information
On seal arrangements of the type described above, such as the arrangement as disclosed by German Laid Open Patent Application No. 1,901,620, a problem can arise as a result of the fluctuations of the clearance between the inner and outer shafts in the vicinity of the inner shaft seal. Thus, a correct seal can generally not be guaranteed, because either excessive pressure is applied to the seal lips fastened rigidly to the outer shaft, thus compressing the seal lips, or insufficient pressure is applied to the seal lips, thus adversely affecting the ability of the seal lips to seal out water.